Study on the Fertility of Vegetable Soil and Controlling Technique for Pollution of Nitrate in Vegetable Crops II.Local Conditions and Fertility Properties of the Chief Type Vegetable Soil in the Suburb of Changsha

By field investigation and sampling and laboratory analysis,this paper is an attempt to study the local conditions and fertility properties of the chief type vegetable soils of 6 bases in the suburb of Changsha.The results show that the vegetable soils are developed from the alluvial deposit in the alluvial terrance and quarternary red clay in the hilly valley and are located in the lower smooth terrain.The soil texture ranges from lightly loamy to heavily loamy,and is suitable to crop growth.The nutrient status of the vegetable soils in the suburb of Changsha was good on the whole,the contents of organic matter,nitrogen,phosphorus and potassium were all at the very high level,and especially the content of phosphorus was much higher than that of the other cultivated soils.Of them the vegetable soils developed from river alluvium has much higher nutrient contents than the reddish vegetable soil developed from Quaternary Red Clay.In the profile 0～75 cm deep,the content of nutrient in most soils always increases with the increase of depth except pH.